In response to readers' questions about how Ashkenazi Jewish genes compare to other groups', Utah anthropologist Henry Harpending sends along a 3d graph he and Greg Cochran created for (but didn't use in) their famous paper on the evolution of high IQs among Ashkenazi Jews.
You can click on the graph to see it in a larger, more readable version. The main left to right axis is the first Principal Component, accounting for 45% of the variance. The axis running from the middle bottom to the upper right is the second Principal Component, accounting for 25%, while the vertical axis is the third PC, accounting for 15%.
As always, the principal components methodology doesn't tell you what the axes mean. That's just how the data cluster and you've got to come up with insights to figure out why. (Don't look to me for them.)
On the first two axes, Ashkenazi Jews are rather close to "Europeans" and "Russians." They are similar to Yemenites (from Southern Arabian peninsula) on the first axis, but not on the second. And they are similar to Samaritans (who currently subsist on two hilltops in Israel), good, bad or indifferent, on the second axis but not on the first. They are fairly similar to the Druze (of Lebanon and Israel) on the first two axes, but not on the third.
On the other hand, if you included some Australian Aborigines, Bushmen and Tierra del Fuegans on this graph, probably all six of these data points would look clustered fairly closely together.
So, Ashkenazis look pretty European on this chart compared to a few Middle Eastern groups. But, as the recent graph showed, genetics has progressed to the point where Ashkenazis (at least those with four Ashkenazi grandparents) can now be reliably distinguished from other Europeans.
Tautologically enough, when it comes to ancestry, everything is relative.